1991 MITSUBISHI 3000GT lock

SERVICE BRAKES -Anti-lock Braking System Troubleshooting
35-35
IGNITIONSWITCH(IG2)
R&RRELAY
DIODE
KX35-AK-R35028PREVIOUS PAGE
With the ignition key in the
“ON” position, does voltage
between ECU connector
terminal No. 18 and ground
indicate the battery voltage?
Is there continuity between
body harness terminals No. 9
and No. 34, and ground?
Repair harness.
vNoIs there continuity between-body harness connector ter-diagnosis inspection
minals No. 23 and No. 24,terminal and ABS ECU
and diagnosis inspection ter-
minals No. 4 & No. 1 O?Yes
”Malfunction of ABS ECU
Replace ABS ECU.
TSB Revision

35-36\
SERVICE BRAKES -‘\Anti-lock Braking System Troubleshooting
CABS warning light does not illuminate when the ignition key is in the “START” position.
[Explanation]
The ABS ECU uses the
IG2 power source which is
turned off in the “START” position. The ABS
warning light uses the
IG, power source which is
not turned off even in the “START” position.
Consequently, in the “START” position, power is off
LJand the ECU turns the valve relay OFF. If the
warning light does not illuminate at this time, there
is trouble in the warning light circuit on the valve
relay side.
EfiE-
9B
wIGNSW1--
J/BF
COMBINATIONMETER
G-R 11 G-
IN;IGl)
ITSB IRemove the hydraulic
unit (HU) connector andcheck.
Yes
c-No -Is there continuity between-> Broken line between HUbody connector terminal No. 9
and body ground
and ground?
-No 7Is there continuity between> Valve relay malfunction orHU connector terminal No. 8
break in HU harness wire
and terminal No. 9?
YesYes
&
Replace valve relay.I
1
HU harness malfunctionj Replace HU.
NOTEWhen performing the check marked *, note polarity of the diode
(refer to the circuit diagram).
visionI

SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-37
DABS warning light blinks once after the ignition key is turned to the “ON” position. It
Lilluminates in the “START” position and blinks once again when turned to the “ON” position.
[Explanation]
1 sec. while itharness between the ECU and the warning light, the
light illuminates only when the valve relay is off in
performs a valve relay test. If there is a break in the
the valve relay test, etc.
IGNITIONSWITCH(IG1)I
J/B
F
2
r+im
md
/
L/
COMBINATION
METER
ABS-ECU-____
KK35-KK-It3503In the ignition key “ON”
position, does voltage
between terminal No. 25 and
ground indicate battery
voltage?ABS warninglight and
Yes
Repair harness.
vMalfunction of ABS ECU
+ Replace ABS ECU.
TSB Revision

[Explanation][Hint]
The ABS ECU detects breaks in the wheel speedIn addition to a broken wire/short circuit in the wheel
sensor wire. This trouble code is output if the wheelspeed sensor, also check whether the sensor gap is
speed sensor signal is not input (or short circuited)too large, sensor harness wire is broken, or sensor
or if its output is low when starting to drive or whileharness and body connector are not properly con-
driving.
netted.E-2 When diagnosis code“15 VEH. SPD. SNSR.” is displayed
[Explanation]l Broken sensor harness
This trouble code is output when there is anl Poor connection of connector
abnormality (other than broken wire or short circuit)
NOTEin any of the wheel speed sensor output signals
(1) If contact is poor, check the sensor cable by
while driving.bending and lightly stretching it.
[Hint](2) Except for the case where a fault condition
The following can be considered as the cause of theexists in the system, but the inspection results
wheel speed sensor output abnormality.are normal; if an abnormality cannot be found in
l Distortion of rotor, teeth missingthe sensor. circuit displayed as abnormal, erase
lLow frequency noise interference when sensorthe diagnosis code and turn the ignition switch
harness wire is brokento OFF once, and then test-drive again.
l Noise interference in sensor signalIf the same trouble code is output, replace the
lSensor output signal is below the standard valueABS ECU. If the trouble does not occur any-or amplitude modulation is over the standardmore, the problem is likely to be with the ABS
ECIJ.\value. Using an oscilloscope to measure the
wave shape of the wheel speed sensor output
signal is very effective.
I\-- -.(If the trouble is in the speed sensor circuit, butdis difficult to recreate, it will recur even after the
ABS ECU has been replaced.)35-38
SERVICE BRAKES -Anti-lock Braking System Troubleshooting
E-lWhen the following diagnosis codes are displayed “11 FR SNSR. OPEN”
“12 FL SNSR. OPEN” “13 RR SNSR. OPEN” “14
RL SNSR. OPEN”
d
SPEED SENSOR
FRONTCLH) FRONTGWR!%R(LH) REARmi
m I@m @
If?All110130125ASS-ECI.+tB5
8
8I
TSB Revision

SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-39
Check flow connected with wheel
speed sensorNOTECheck speed sensor harness and connector connection
and then observe with oscilloscope. (Refer to
P.35-57.)No ,
Is the resistance value of the wheel
speed sensor part normal?
Standard value: 0.8 - 1.2 kR
z Malfunction of wheel speed
sensor
Yes
,I”
/
LY14N0127
L14N0181
1Yes
-NoCheck the output of each
wheel speed sensor with an
oscilloscope, including the
waveform. (Refer to
P.35-57.)Is the output voltage for each
wheel speed sensor over
the standard value and is
the waveform normal?
TSB Revision

35-40SERVICE BRAKES -Anti-lock Braking System Troubleshooting
E-3When diagnosis code “21 G SNSR.” is displayed
[Explanation]
The ABS-ECU outputs this trouble code in the
following cases.
l G sensor OFF trouble (It is judged that the G
sensor continues to be OFF for more than
approximately 13 seconds except when thevehicle is stopped or when there is stop light
switch input.)
lWhen there is a broken wire or short circuit in
the harness for the G sensor system.
FUSIBLE LINK@
4
pilGGRq;
I4
Bd
pEmg=1
--a
2
__1
It
I,1II1 Ii II II II Ii II II I/ II ;/ II II II II !: II//IIII/.--A
X35-LK-R9505
I
IiNo IfIs G sensor normal? (Refer
to
P.35-92.)Replace G sensor.
I
Yes
Remove the ABS-ECU
connector and check at
the harness connector.
With the ignition key “ON”,
does the voltage between
terminal No. 6 and groundindicate battery voltage?
Repair harness.
”
ABS-ECU malfunctionIJP Replace ABS-ECU.
TSB Revision

SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-41E-4 When diagnosis code“22 STOP LAMP SW” is displayed
ii’ [Explanation][Hint]
The ABS-ECU outputs this trouble code in theIf the stop light operates normal, the harness for the
following cases.stop light switch input circuit is broken or there is a
lStop light switch remains on for more than 15malfunction in the ABS-ECU.
minutes while the ABS is not functioning.
lThe harness wire for the stop light switch may
be open.
L
FUSIBLE,LINK@
J/B
0
I
I
ABS-ECU29
j 1 ) 2 13 14) 5 / 6 17 / 9 j 9 ~10~11~12~13(14~15(161171~9~~'9~0l21~2~3l9~~~6~~~9~~0l31l321U13l35l
KX35-AK-33306
F Check the stop light related
go out
normally?circuit and repair problem
spots.
When the brake pedal is pressed
between connector terminal No.
29 and ground indicate battery
I1 voltage! , Yes /Repair harness.
Is the voltage between No.
1terminal and ground equal to the
battery voltage when measured
wrth resistor connector discon-
nected?
YesRepair harness.
6NoIs resistor resistance 780 to
860 sl?) Replace resistor.
YesIs there continuity between No. 2
FpylReplace ABS-ECU.
visionI

35-42SERVICE BRAKES -Anti-lock Braking System Troubleshooting
E-5When diagnosis codes “41 FR SOL. VALVE”,
“42 FL SOL. VALVE” or “43 VALVE DRIFT”
are displayed.
‘LJ[Explanation]
The ABS-ECU normally monitors the solenoid valve
drive circuit.
If no current flows in the solenoid even if the ECU
turns the solenoid ON or if it continues to flow even
when turned OFF, the ECU determines thesolenoid coil wire is broken/short-circuited or the
harness is broken/short-circuited, and then these
trouble codes are output.
ABS-ECU controls the solenoid valve current and if
the current value of the solenoid valves differs from
j:
z!d
9
E6T
mA9f#;NATIOM
I-N----_---____IGNITION
SWITCH(IG2)Fw
"50
fm!EaqG-R
?,I G-RI
X35-AK-K3507each other in the same mode, solenoid valve drift
error is produced and the ABS-ECU goes into the
failsafe mode.
1No
In the resistance value forthe solenoid valve withinthe range of the standard
values?
Standard value: 1.1 - 1.3 R
Yes
”
) Replace HU.
Connect HU 1 OP connector,
\ ci;;;;;;;t EC,U connector,)
Yes
+The harness wire for the
solenoid valve circuit
whose resistance value is
outside the range of the
standard value is brokenor short circuited.
Repair harness.
1 Malfunction of ABS-ECU4 Replace ABS-ECU.I IIII1
TSB Revision